It found that the majority of the Earth's terrestrial store of carbon was in soil, and that as the atmosphere warms up, increasing amounts are emitted in what is a vicious cycle of "positive feedbacks".

The study found that 55bn tonnes in carbon, not previously accounted for by scientists, will be emitted into the atmosphere by 2050.

"As the climate warms, those organisms become more active and the more active they become, the more the soil respires - exactly the same as human beings," said Dr Crowther, who headed up the study at Yale Climate & Energy Institute, but is now a Marie Curiefellow at the Netherlands Institute of Ecology.

"Our study shows that this major feedback has already certainly started, and it will have a significant impact on the climate in the coming decades. This information will be critical as we strive to understand how the climate is going to change in the future. And it will also be critical if we are to generate meaningful strategies to fight against it."

Dr Crowther, a 30-year-old Cardiff University Phd graduate originally from North Wales, predicts climate change will lead to widespread migrations and antagonism among communities.

"These effects of climate change will certainly be felt disproportionately by poorer people, particularly the billions of people whose livelihoods are intrinsically linked to the land," he added.

"But the impacts on sea-level rise, ocean currents and the health of natural ecosystems are equally devastating for a vast multitude of reasons."

"Uncertainty is nothing like a reason enough to suggest climate change isn't happening. There's a nice analogy; if you step in front of an oncoming bus, no doctor in the world can tell you how damaging the impact is going to be.

"But we do know the damage is going to be huge. This alone should be enough information to persuade us to avoid the bus."

The last two decades of the 20th century were the hottest in 400 years.

He added: "Sceptics often say that scientists are just saying that climate change is real so that they can keep their jobs.

"I would just like to stress that I could get a hell of a lot more money than academia offers me if I were to do a study that suggests that climate change is not real."

Prof Ivan Janssens, seen as one of the godfathers in the global change ecology field, said the research had provided essential data to the climate change model.

"This study is very important, because the response of soil carbon stocks to the ongoing warming, is one of the largest sources of uncertainty in our climate models," said Prof Janssens, of the University of Antwerp.

"I'm an optimist and still believe that it is not too late, but we urgently need to develop a global economy driven by sustainable energy sources and start using CO2, as a substrate, instead of a waste product.

"If this happens by 2050, then we can avoid warming above 2C. If not, we will reach a point of no return and will probably exceed 5C."